I mean, typically laws do not substitute for the creative process of designing and marketing buildings. What color should the walls be? What kind of kitchen faucet should you have? What should the countertops be made out of? What flooring surface will you use? There is no reason that "how many parking spaces should we build" be the 1 question that the government answers for you. Make an educated guess. If you're wrong and build too many, you leave money on the table. If you build too few, then people will buy some other unit with more parking.
> What color should the walls be? What kind of kitchen faucet should you have? What should the countertops be made out of? What flooring surface will you use?
All of these can very easily be changed by future buyers if they prefer something different.
But if the developers builds a 50 unit apartment building with just 4 parking spots, that building is now there for many generations and there is no practical way to change that decision.
That doesn't provide any guidance to the builder though, so what should they build?